jamyskis: Not so much "arbitrary", more a "guide". There are more factors involved than just wishlist votes, among them where did the votes come from. For instance, if someone on the forum organises a giveaway in exchange for votes for a certain game, that might reduce the value of those votes in GOG's eyes. Some people vote for a game out of some misguided loyalty towards a developer, even though they have the game on Steam or Humble already and have no intention of buying the game on GOG.
That's more true than one might expect. GOG has publicly stated in the forums that giveaways or other mechanisms designed to coerce people into voting for a game does indeed devalue that game's wishlist score value and that they do take note of this when determining the perceived demand for a game. That probably affects prioritization more than any yes/no decision about trying to get a game in the first place though. Anything that artificially inflates demand like this will be noticed and likely not have the effect that the inflater intended. What's sad is that in many if not most cases the people doing the inflating do not realize that they're essentially gaming the system and causing more harm to the cause than good. A better way for people to go about it would be perhaps to say something more like:
"This is not required to enter my giveaway but here are a number of games to check out which you might be interested in. If you think they look cool and you might be interested in buying them if they were to come to GOG, consider voting for them on the GOG wishlist:
<links to trailers, articles, websites, whatever for various games>
<links to GOG wishlist entry for each game>"
This way they're not saying "vote for this game whether or not you care about it, and magically get a chance to win a game" which harms the system with artificially inflated votes for games nobody may actually care about, but instead it encourages people to look at trailers and game details and decide for themselves if they like it and possibly vote for it if they do.
jamyskis: I'll give you a classic example: Cave Story+. It has (as of now) 1788 votes on the wishlist. It owes many of those votes to Barry_Woodward constantly organising giveaways and posting new threads about it. Had there been no such campaigning, it probably would have barely broken the three-digit threshold. Not to mention that many people in the comments there openly state that they have the game from indie bundles and on Steam already. In fact, I don't think there's a single indie game on that list that's broken the 2000 vote barrier. Everything from 2000 votes is AAA/mainstream. That's what sells.
This is a generic comment not directed at anyone but just generalizing. If people want to increase the interest in a given game in others and do so in a positive and encouraging way that means something it would be better to point people to information resources on the games in question like I said above. Game trailers, developer interviews, game websites and other promotional materials, gameplay videos on youtube and encourage people to have a look at them and decide for themselves, but never to make entering a contest contingent on voting for any games and to explicitly state that voting is not required nor expected. Be as neutral as possible. Let the games videos and other materials stand up on their own to sell the game, don't try to forge the popularity beyond what it really is - work to increase the popularity by helping passionately market the game by sharing info about it to try to garner interest - but also doing it in a way that is not deemed a spammy nuisance also.
I agree with your assessment though and I can't see GOG welcoming bucketfulls of non-selling indie shovelware here just because there are a small vocal minority of people who evangelize the particular game(s) who are upset it isn't getting the attention they want them to have. There may be the odd exception from time to time but the exceptions do not make the rule. Also, sometimes GOG re-evaluates past decisions over time and changes their minds based on overwhelming feedback too. I think "Braid" and "Meridian: Squad 22" are two examples of this in recent memory.
Mind you I think they should sometimes do the reverse too and re-evaluate some decisions of games they did bring here that they should remove and reject post-facto, like No Man's Sky and that "DRM-free Edition" indie board game that's getting the shit kicked out of it lately. :)